I don't put any weed killer on my lawn either -- have a mulching mower so I don't bag grass clippings and gradually over the last few years, the grass has overtaken the weeds that were here when the house was bought several years ago. Also don't scalp my lawn so the grass is choking out the weeds. As my Dad always said -- weeds are green so just mow them off.
Only vegetation killer I used was for the poison ivy that was in the brook in the back of the property.
It's amazing to me how so many people use so much energy and crud to create unsustainable and dangerous green expanses of plain old lawn. My lawn areas keep getting smaller and smaller each year, and my gardens and naturalized plantings, like blue festuca, keep expanding. One of the wonderful benefits of snow on the mountain, (other than it doesn't need mowing or watering), invasive though it is, is that it hides a lot of piles of dog poop, LOL!